The goal of the research is to determine those mechanisms which permit ovarian follicles to ovulate in response to the pituitary gonadotropin, LH. Steroids, prostaglandins and enzymatic degradation of the follicular wall have all been implicated as mediators of the LH-induced ovulatory process. However, the mechanisms by which LH, steroids, and prostaglandins interact to control ovulation remain unclear. Therefore, the specific aims of the proposed research are: 1) to determine the effects of hormones and stage of follicular growth on thecal cell differentiation in vivo and in vitro; 2) to determine the effects of hormones and stage of follicular growth on the production of prostaglandins by thecal and granulosa cells; and 3) to determine some of the mechanisms by which the preovulatory follicle ruptures and reorganizes itself into a corpus luteum. Using thecal cell cultures we intend to determine in what cell types, at what stage of follicular development and by what mechanisms LH, steroids and prostaglandins regulate thecal cell responsiveness to LH and ovulation. The thecal cell cultures will be especially invaluable in determining the hormonal regulation of collagenase synthesis, secretion and activation because (pro)collagenase is secreted by, rather than stored in, the cells in which it is made. The content of (pro)collagenase in tissue and media samples will be quantified by Elisa assay and immunoblotting procedures; the activity of collagenase will be measured using 3H-labeled collagen substrate. Thecal cell cultures will also be important for determining the sites and hormonal control of collagen synthesis. Quantitative analyses of collagen and collagenase will be related to immunofuorescent localization of types I, III and IV collagen and their specific collagenases. By unraveling the intrafollicular control of prostaglandin synthesis and action, as well as of collagenase activity, LH control of ovulation should begin to be elucidated.